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e2fsprogs
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ChangeLog, ext2_io.h, unix_io.c: 

unix_io.c: Make massive changes to support a multiple block
  	writethrough cacheing.
  ext2_io.h: Added flags field to the io_channel structure.
bitmap-optimize
Theodore Ts'o 2000-10-18 19:22:24 +00:00
parent ad8e553bc6
commit adfc8c6c99
3 changed files with 326 additions and 86 deletions
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7
lib/ext2fs/ChangeLog
View File

@ -1,3 +1,10 @@
2000-08-22 <tytso@valinux.com>
* unix_io.c: Make massive changes to support a multiple block
writethrough cacheing.
* ext2_io.h: Added flags field to the io_channel structure.
2000-08-19 <tytso@valinux.com>
* finddev.c, ext2fs.h, Makefile.in: Add new file, finddev.c, which

5
lib/ext2fs/ext2_io.h
View File

@ -27,6 +27,8 @@ ext2_loff_t ext2fs_llseek (int, ext2_loff_t, int);
typedef struct struct_io_manager *io_manager;
typedef struct struct_io_channel *io_channel;
#define CHANNEL_FLAGS_WRITETHROUGH 0x01
struct struct_io_channel {
errcode_t magic;
io_manager manager;
@ -47,7 +49,8 @@ struct struct_io_channel {
int actual_bytes_written,
errcode_t error);
int refcount;
int reserved[15];
int flags;
int reserved[14];
void *private_data;
void *app_data;
};

400
lib/ext2fs/unix_io.c
View File

@ -45,13 +45,24 @@
#define EXT2_CHECK_MAGIC(struct, code) \
if ((struct)->magic != (code)) return (code)
struct unix_cache {
char *buf;
unsigned long block;
int access_time;
int dirty:1;
int in_use:1;
};
#define CACHE_SIZE 8
#define WRITE_VIA_CACHE_SIZE 4 /* Must be smaller than CACHE_SIZE */
struct unix_private_data {
int magic;
int dev;
int flags;
char *buf;
int buf_block_nr;
int access_time;
struct unix_cache cache[CACHE_SIZE];
};
static errcode_t unix_open(const char *name, int flags, io_channel *channel);
@ -76,6 +87,208 @@ static struct struct_io_manager struct_unix_manager = {
io_manager unix_io_manager = &struct_unix_manager;
/*
* Here are the raw I/O functions
*/
static errcode_t raw_read_blk(io_channel channel,
struct unix_private_data *data,
unsigned long block,
int count, void *buf)
{
errcode_t retval;
size_t size;
ext2_loff_t location;
int actual = 0;
size = (count < 0) ? -count : count * channel->block_size;
location = (ext2_loff_t) block * channel->block_size;
if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
actual = read(data->dev, buf, size);
if (actual != size) {
if (actual < 0)
actual = 0;
retval = EXT2_ET_SHORT_READ;
goto error_out;
}
return 0;
error_out:
memset((char *) buf+actual, 0, size-actual);
if (channel->read_error)
retval = (channel->read_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
static errcode_t raw_write_blk(io_channel channel,
struct unix_private_data *data,
unsigned long block,
int count, const void *buf)
{
size_t size;
ext2_loff_t location;
int actual = 0;
errcode_t retval;
if (count == 1)
size = channel->block_size;
else {
if (count < 0)
size = -count;
else
size = count * channel->block_size;
}
location = (ext2_loff_t) block * channel->block_size;
if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
actual = write(data->dev, buf, size);
if (actual != size) {
retval = EXT2_ET_SHORT_WRITE;
goto error_out;
}
return 0;
error_out:
if (channel->write_error)
retval = (channel->write_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
/*
* Here we implement the cache functions
*/
/* Allocate the cache buffers */
static errcode_t alloc_cache(io_channel channel,
struct unix_private_data *data)
{
errcode_t retval;
struct unix_cache *cache;
int i;
data->access_time = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
cache->block = 0;
cache->access_time = 0;
cache->dirty = 0;
cache->in_use = 0;
if ((retval = ext2fs_get_mem(channel->block_size,
(void **) &cache->buf)))
return retval;
}
return 0;
}
/* Free the cache buffers */
static void free_cache(io_channel channel,
struct unix_private_data *data)
{
struct unix_cache *cache;
int i;
data->access_time = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
cache->block = 0;
cache->access_time = 0;
cache->dirty = 0;
cache->in_use = 0;
if (cache->buf)
ext2fs_free_mem((void **) &cache->buf);
cache->buf = 0;
}
}
/*
* Try to find a block in the cache. If get_cache is non-zero, then
* if the block isn't in the cache, evict the oldest block in the
* cache and create a new cache entry for the requested block.
*/
struct unix_cache *find_cached_block(io_channel channel,
struct unix_private_data *data,
unsigned long block,
int get_cache)
{
struct unix_cache *cache, *free_cache, *oldest_cache;
int i;
free_cache = oldest_cache = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
if (!cache->in_use) {
free_cache = cache;
continue;
}
if (cache->block == block) {
cache->access_time = ++data->access_time;
return cache;
}
if (!oldest_cache ||
(cache->access_time < oldest_cache->access_time))
oldest_cache = cache;
}
if (!get_cache)
return 0;
/*
* Try to allocate cache slot.
*/
if (free_cache)
cache = free_cache;
else {
cache = oldest_cache;
if (cache->dirty)
raw_write_blk(channel, data,
cache->block, 1, cache->buf);
}
cache->in_use = 1;
cache->block = block;
cache->access_time = ++data->access_time;
return cache;
}
/*
* Flush all of the blocks in the cache
*/
static errcode_t flush_cached_blocks(io_channel channel,
struct unix_private_data *data,
int invalidate)
{
struct unix_cache *cache;
errcode_t retval, retval2;
int i;
retval2 = 0;
for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
if (!cache->in_use)
continue;
if (invalidate)
cache->in_use = 0;
if (!cache->dirty)
continue;
retval = raw_write_blk(channel, data,
cache->block, 1, cache->buf);
if (retval)
retval2 = retval;
else
cache->dirty = 0;
}
return retval2;
}
static errcode_t unix_open(const char *name, int flags, io_channel *channel)
{
io_channel io = NULL;
@ -110,11 +323,10 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
memset(data, 0, sizeof(struct unix_private_data));
data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
retval = ext2fs_get_mem(io->block_size, (void **) &data->buf);
data->buf_block_nr = -1;
if (retval)
goto cleanup;
if ((retval = alloc_cache(io, data)))
goto cleanup;
open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
#ifdef HAVE_OPEN64
data->dev = open64(name, open_flags);
@ -129,13 +341,12 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
return 0;
cleanup:
if (io)
ext2fs_free_mem((void **) &io);
if (data) {
if (data->buf)
ext2fs_free_mem((void **) &data->buf);
free_cache(io, data);
ext2fs_free_mem((void **) &data);
}
if (io)
ext2fs_free_mem((void **) &io);
return retval;
}
@ -150,11 +361,12 @@ static errcode_t unix_close(io_channel channel)
if (--channel->refcount > 0)
return 0;
retval = flush_cached_blocks(channel, data, 0);
if (close(data->dev) < 0)
retval = errno;
if (data->buf)
ext2fs_free_mem((void **) &data->buf);
free_cache(channel, data);
if (channel->private_data)
ext2fs_free_mem((void **) &channel->private_data);
if (channel->name)
@ -173,12 +385,13 @@ static errcode_t unix_set_blksize(io_channel channel, int blksize)
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (channel->block_size != blksize) {
channel->block_size = blksize;
ext2fs_free_mem((void **) &data->buf);
retval = ext2fs_get_mem(blksize, (void **) &data->buf);
if (retval)
if ((retval = flush_cached_blocks(channel, data, 0)))
return retval;
channel->block_size = blksize;
free_cache(channel, data);
if ((retval = alloc_cache(channel, data)))
return retval;
data->buf_block_nr = -1;
}
return 0;
}
@ -188,96 +401,111 @@ static errcode_t unix_read_blk(io_channel channel, unsigned long block,
int count, void *buf)
{
struct unix_private_data *data;
struct unix_cache *cache;
errcode_t retval;
size_t size;
ext2_loff_t location;
int actual = 0;
int i, j;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
/*
* If it's in the cache, use it!
* If we're doing an odd-sized read, flush out the cache and
* then do a direct read.
*/
if ((count == 1) && (block == data->buf_block_nr)) {
memcpy(buf, data->buf, channel->block_size);
return 0;
if (count < 0) {
if ((retval = flush_cached_blocks(channel, data, 0)))
return retval;
return raw_read_blk(channel, data, block, count, buf);
}
#if 0
printf("read_block %lu (%d)\n", block, count);
while (count > 0) {
/* If it's in the cache, use it! */
if ((cache = find_cached_block(channel, data, block, 0))) {
#ifdef DEBUG
printf("Using cached block %d\n", block);
#endif
size = (count < 0) ? -count : count * channel->block_size;
location = (ext2_loff_t) block * channel->block_size;
if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
actual = read(data->dev, buf, size);
if (actual != size) {
if (actual < 0)
actual = 0;
retval = EXT2_ET_SHORT_READ;
goto error_out;
}
if (count == 1) {
data->buf_block_nr = block;
memcpy(data->buf, buf, size); /* Update the cache */
memcpy(buf, cache->buf, channel->block_size);
count--;
block++;
buf += channel->block_size;
continue;
}
/*
* Find the number of uncached blocks so we can do a
* single read request
*/
for (i=1; i < count; i++)
if (find_cached_block(channel, data, block+i, 0))
break;
#ifdef DEBUG
printf("Reading %d blocks starting at %d\n", i, block);
#endif
if ((retval = raw_read_blk(channel, data, block, i, buf)))
return retval;
/* Save the results in the cache */
for (j=0; j < i; j++) {
count--;
cache = find_cached_block(channel, data, block++, 1);
if (cache)
memcpy(cache->buf, buf, channel->block_size);
buf += channel->block_size;
}
}
return 0;
error_out:
memset((char *) buf+actual, 0, size-actual);
if (channel->read_error)
retval = (channel->read_error)(channel, block, count, buf,
size, actual, retval);
return retval;
}
static errcode_t unix_write_blk(io_channel channel, unsigned long block,
int count, const void *buf)
{
struct unix_private_data *data;
size_t size;
ext2_loff_t location;
int actual = 0;
errcode_t retval;
struct unix_cache *cache;
errcode_t retval = 0, retval2;
char *cp;
int i, writethrough;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
if (count == 1)
size = channel->block_size;
else {
data->buf_block_nr = -1; /* Invalidate the cache */
if (count < 0)
size = -count;
else
size = count * channel->block_size;
}
location = (ext2_loff_t) block * channel->block_size;
if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
goto error_out;
}
actual = write(data->dev, buf, size);
if (actual != size) {
retval = EXT2_ET_SHORT_WRITE;
goto error_out;
/*
* If we're doing an odd-sized write or a very large write,
* flush out the cache completely and then do a direct write.
*/
if (count < 0 || count > WRITE_VIA_CACHE_SIZE) {
if ((retval = flush_cached_blocks(channel, data, 1)))
return retval;
return raw_write_blk(channel, data, block, count, buf);
}
if ((count == 1) && (block == data->buf_block_nr))
memcpy(data->buf, buf, size); /* Update the cache */
/*
* For a moderate-sized multi-block write, first force a write
* if we're in write-through cache mode, and then fill the
* cache with the blocks.
*/
writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
if (writethrough)
retval = raw_write_blk(channel, data, block, count, buf);
return 0;
error_out:
if (channel->write_error)
retval = (channel->write_error)(channel, block, count, buf,
size, actual, retval);
while (count > 0) {
cache = find_cached_block(channel, data, block, 1);
if (!cache) {
/*
* Oh shit, we couldn't get cache descriptor.
* Force the write directly.
*/
if ((retval2 = raw_write_blk(channel, data, block,
1, buf)))
retval = retval2;
} else {
memcpy(cache->buf, buf, channel->block_size);
cache->dirty = !writethrough;
}
count--;
block++;
buf += channel->block_size;
}
return retval;
}
@ -287,12 +515,14 @@ error_out:
static errcode_t unix_flush(io_channel channel)
{
struct unix_private_data *data;
errcode_t retval = 0;
EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
data = (struct unix_private_data *) channel->private_data;
EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
retval = flush_cached_blocks(channel, data, 0);
fsync(data->dev);
return 0;
return retval;
}